In 1963, Gifford et. al invented the first tube pulse refrigerator, known as basic type (U.S. Pat. No. 3,237,421). In 1984, Mikulin et. al provides an improved pulse tube refrigerator (USSR Patent No. SU553414) with a reservoir volume and an orifice member between the reservoir volume and the pulse tube. This refrigerator achieves a great improvement in performance and show its great potential of application on cryogenic circumstance.
A double-inlet pulse tube refrigerator is disclosed in Chinese Patent No. CN 89214250.2 by S. Zhu et. al, as shown in FIG. 1. The refrigerator includes a pressure wave generator 1, a regenerator 2, a heat exchanger of cold ends (cold finger) 3, a pulse tube 5, a throttling member 8 and a reservoir volume 9, connecting in serial. The regenerator 2 connects with the pressure wave generator at its hot end 2'. The cold end 2" of the regenerator 2 is connected with the cold end 5" of the pulse tube 5 by the heat exchanger 3. The reservoir volume 9 is connected with the hot end 5' of the pulse tube through the throttling member 8. Rectifying members 4 and 6 are arranged at the ends of the pulse tube 5. Screen is packed in the regenerator 2. Devices 7 and 10 may be provided near the hot ends 2', 5' and the cold finger 3 to strengthen heat transfer. Moreover, at the outlet of the pressure wave generator 1, a gas flow is diverted and enters the pulse tube 5 at its hot end 5' through a tube 12 with a throttling member 11. However the refrigerator has a limited maximum refrigeration capacity and minimum refrigeration temperature, although its refrigeration efficiency has been improved somewhat, resulting from the rigidity of the driven gas column (supposed as a gas piston in shape of the driven gas column) is less than that of the driven solid piston used in other cryocooler. Thus the effect of the refrigerator is not satisfied.
Accordingly, the object of the present invention is to provide a multi-bypass pulse tube refrigerator with improved refrigeration efficiency, much lower refrigeration temperature and increased refrigeration capacity.